RU2548912C2 - Functional fluid compositions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: claimed invention relates to functional fluid composition, containing: (a) from 70% to 99.99%, of weight of functional fluid composition, of basic oil composition, which contains: (i) from 50% to 95%, of weight of basic oil composition, of naphthene basic oil; (ii) from 5% to 50%, of weight of basic oil composition, of basic oil, produced in Fischer-Tropsch synthesis, with functional fluid composition having flow point, equal -30°C or lower. Claimed invention also relates to hydraulic fluid composition, to shock-absorber fluid and to application of functional fluid composition for reduction of degree of synthetic rubber swelling.

EFFECT: creation of functional fluid composition aimed at reduction of degree of synthetic rubber swelling.

10 cl, 3 ex, 11 tbl

Description

FIELD OF THE INVENTION

The present invention relates to compositions of a functional fluid, specifically to compositions of a functional fluid that are used as hydraulic fluids and shock absorber fluids and which have improved swelling properties of the gaskets.

State of the art

Typically, mineral-based aviation hydraulic fluids use naphthenic base mineral oils in order to meet the low temperature properties that are required by army specifications for these products, namely MIL-PRF-5606 and MIL-PRF-6083. These specifications state that products conforming to the standard must comply with the requirement regarding swelling of synthetic rubber. In particular, it is required that when testing hydraulic fluids according to the FED-STD-791D-3605.5 method, the elastomer swell rate should be between 19 and 30% for MIL-PRF-5606 and between 19 and 28% for MIL-PRF-6083. Unfortunately, naphthenic base oils can cause excessive swelling of the synthetic rubber, and in some cases, the hydraulic fluid becomes unusable according to the test of technical conditions, which leads to failure of the product or to an undesirable product. This problem is complicated by global restrictions on the supply of naphthenic base oils and a general loss of availability.

Therefore, it would be desirable to develop a naphthenic base hydraulic fluid that meets the mandatory requirements regarding the degree of elastomer swelling.

SUMMARY OF THE INVENTION

According to the present invention, a composition of a functional fluid suitable for use as a hydraulic fluid or shock absorber fluid, which contains:

(a) from 70% to 99.99%, by weight of the composition of the functional fluid, the composition of the base oil containing:

(i) from 50% to 95%, by weight of the composition of the base oil, naphthenic base oil; and

(ii) from 5% to 50%, by weight of the composition of a base oil, a base oil produced in the Fischer-Tropsch synthesis.

In addition, the present invention relates to hydraulic shock absorbers and hydraulic systems comprising a functional fluid composition according to the present invention.

It was unexpectedly found that by replacing part of the naphthenic base oils used in hydraulic fluids and shock absorbing fluids with a base oil made in the Fischer-Tropsch synthesis, the observed degree of swelling of synthetic rubber can be significantly reduced, according to the test method FED-STD-791D-3605.5.

Therefore, according to the present invention, the use of a functional fluid composition has been developed, as described below, in order to reduce the degree of swelling of synthetic rubber.

In addition, it was found that the combination of a naphthenic base oil of mineral origin and a base oil produced in the Fischer-Tropsch synthesis allows to obtain a functional fluid composition that has an increased specific heat capacity compared to traditional hydraulic fluids containing only naphthenic base oils of mineral origin, which helps to reduce the thermal destruction of the functional fluid during operation and extends the effective life of the product.

Additionally, it was found that for the composition of the functional fluid of the present invention, there is a significant reduction in product losses due to evaporation compared to functional fluid compositions containing only naphthenic base oils.

DETAILED DESCRIPTION OF THE INVENTION

The functional fluid composition of the present invention contains, as an essential component, a base oil composition.

The specified base oil composition is present in the concentration range from 70% to 99.99% by weight, preferably in the range from 75% to 90% by weight, more preferably in the range from 80% to 85% by weight.

According to the invention, one essential component of the base oil composition is a naphthenic base oil of mineral origin.

Used in the invention, the term "naphthenic content" in naphthenic base oil is defined as the mass percentage of all molecules with mono- and polycycloparaffin functional groups. Naphthenes can be determined using a combination of liquid chromatographic separation methods by HPLC, field ionization mass spectrometry (FIMS) and proton NMR for olefins, which are described as follows.

Preferably, the naphthenes content in the naphthenic base oil for use according to the invention is in the range from 50% to 90%, more preferably in the range from 60% to 80%, by weight of the naphthenic base oil.

Mineral naphthenic base oil is present in a concentration range from 50% to 95%, preferably in a range from 70% to 95%, more preferably in a range from 75% to 85%, by weight of the base oil composition.

There are no particular restrictions on the type of naphthenic base oil of mineral origin that can be used in the base oil composition of the invention. Any naphthenic base oil of mineral origin that is suitable for use in a hydraulic fluid composition or a shock absorber fluid composition may be used in the functional fluid composition of the invention.

Naphthenic base oils are defined as Group V base oils by the American Petroleum Institute (API) classification.

The specified base oils of mineral origin are obtained using refining processes based on naphthenic crude oil. The naphthenic base oils of mineral origin used in the present invention preferably have a pour point below -20 ° C and a viscosity index of less than 70. Such base oils are made from naphthenic enriched raw materials and are low in paraffin content. Mineral naphthenic base oils are well known and described in more detail in the book “Lubricant base oil and wax processing”, Avilino Sequeira, Jr., Marcel Dekker, Inc, New York, 1994, ISBN 0-8247 -9256-4, p. 28-35.

Methods for preparing naphthenic base oils can be found in the book “Lubricants and Lubrication (Second Edition, Completely Revised and Supplemented),” published by Wiley-VCH Verlag GmbH & Co. KgaA, Chapter 4, pp. 46-48.

Commercially available sources of naphthenic base oils include those available under the HYDROCAL trademark from Calumet Lubricants Co., commercially available oils under the HYPRENE and HYGOLD trademark from Ergon Petroleum Specialties, the industrially available nynfene base oils from Nynas, and SNH naphthenic base oils commercially available from Sankyo-Yuku.

Particularly preferred naphthenic base oils for use in the invention have a kinematic viscosity at 20 ° C. in the range of 4.75 to 5.10 mm ² / s, kinematic viscosity at 40 ° C. in the range of 2.90 to 3.20 mm ² / s, a minimum flash point (ASTM D92 standard) of 101 ° C and a minimum yield temperature of -66 ° C.

An additional essential component of the base oil composition according to the invention is a Fischer-Tropsch derived base oil.

Used in the invention, the term “produced in the Fischer-Tropsch synthesis” means that the material is a condensation product of the Fischer-Tropsch synthesis or made from it. The product produced in the Fischer-Tropsch synthesis may also be called the product “GTL (Gas to Liquid Fuel)”.

The Fischer-Tropsch derived base oil for use in the invention preferably has a kinematic viscosity at 100 ° C. (according to ASTM D445) in the range of 0.5 to 5 mm ² / s.

Fischer-Tropsch condensation synthesis is a process in which carbon monoxide and hydrogen are converted to long chain hydrocarbons, usually to paraffinic hydrocarbons:

n (CO + 2H ₂ ) = (- CH _2- ) _n + nH ₂ O + heat,

in the presence of a suitable catalyst and usually at elevated temperature (for example, from 125 to 300 ° C, preferably from 175 to 250 ° C) and / or pressure, for example, from 5 to 100 bar (0.5 to 10.0 MPa), preferably from 12 to 50 bar (1.2-5 MPa). Optionally, hydrogen: carbon monoxide ratios other than 2: 1 can be used.

A mixture of carbon monoxide and hydrogen can be obtained from organic or inorganic, natural or synthetic sources, usually either from natural gas or from methane of organic origin. In general, gases that are converted into liquid fuel components using Fischer-Tropsch synthesis may include natural gas (methane), liquefied petroleum gas (LNG, for example propane or butane), “condensates” such as ethane, synthesis gas (CO / hydrogen) and gaseous products made from coal, biomass and other hydrocarbons.

Fischer-Tropsch synthesis can be used to produce a number of hydrocarbon fuels, including fractions of LNG, naphtha, kerosene and gas oil. Of these fractions, gas oils are used as automobile diesel fuel compositions, usually in mixtures with gas oils of petroleum origin. After heavier fractions, after hydrotreating and vacuum distillation processes, a number of base oils with various distillation characteristics and viscosities that are used as raw materials for a lubricating base oil can be obtained.

Hydrocarbon products can be obtained directly in the Fischer-Tropsch synthesis or indirectly, for example, by fractionation of the Fischer-Tropsch synthesis products or from the Fischer-Tropsch synthesis products after hydrotreating. Hydrotreating may include hydrocracking to adjust the boiling range, and / or hydroisomerization, which can improve cold flow properties by increasing the proportion of branched paraffins. Other processing methods after this synthesis, such as polymerization, alkylation, distillation, cracking decarboxylation, hydromerization and hydroreforming, can be used to modify the properties of the condensation products of the Fischer-Tropsch synthesis.

Typical Fischer-Tropsch synthesis catalysts for the production of paraffinic hydrocarbons contain, as a catalytically active component, a metal from group VIII of the periodic system of elements, especially ruthenium, iron, cobalt or nickel. Examples of suitable catalysts are described, for example, in document EP 0583836 (pages 3 and 4).

An example of a method based on the Fischer-Tropsch synthesis is the SMDS (Synthesis middle distillate company Shell), which describes van der Burgt et al. In the publication "The Shell Middle Distillate Synthesis Process" , presented at the 5 ^th International Symposium on synthetic fuel, Washington DC, November 1985; see also the publication of Shell International Petroleum Company Ltd, London, UK in November 1989. In this method (sometimes also referred to as Shell fuel gas production method or “GTL” technology) products in the middle distillate range are obtained by converting synthesis gas, produced from natural gas (mainly methane) into long-chain heavy hydrocarbons (paraffin wax), which can then be hydroconverted and fractionated in order to produce a liquid transport fuel such as gas oil used in diesel compositions. Base oils, including heavy base oils, can also be obtained in the specified method. A variant of the SMDS process using a fixed bed reactor in a conversion step is currently being operated in Bintulu, Malaysia. The produced gas oil fractions are mixed with gas oils of petroleum origin to produce industrially available automotive fuel.

Thanks to the Fischer-Tropsch synthesis, base oils are obtained that practically do not contain (at the detection level) sulfur and nitrogen. Compounds containing these heteroatoms have a toxic effect on Fischer-Tropsch synthesis catalysts and are therefore removed from the starting synthesis gas. This may provide additional benefits for the composition of the functional fluid according to the present invention.

In addition, in the normal mode of operation in the Fischer-Tropsch synthesis, aromatic components are not formed or almost do not form. The content of aromatic components in the Fischer-Tropsch derived base oil is accordingly determined according to ASTM D-4629 and can usually be below 1 wt.%, Preferably below 0.5 wt.% And more preferably below 0.1 wt.% per mole (but not per atom).

Generally speaking, hydrocarbon products produced in the Fischer-Tropsch synthesis have a relatively low content of polar components, especially polar surfactants, for example, compared with hydrocarbons of petroleum origin. This may contribute to the improvement of anti-foaming characteristics of defoaming and haze characteristics. Such polar components may include, for example, oxygen containing compounds and compounds containing sulfur and nitrogen. The low sulfur content of hydrocarbons produced in the Fischer-Tropsch synthesis usually also indicates a low content of both oxygen-containing and nitrogen-containing compounds, since they are removed in the same processing processes.

According to the invention, the Fischer-Tropsch derived base oil is present in the composition of the functional fluid in a concentration of at least 5%, preferably at least 10%, more preferably at least 15%, by weight of the composition of the functional fluid.

Preferably, the Fischer-Tropsch derived base oil is present in the functional fluid composition at a concentration of at least 50%, more preferably at least 40% and even more preferably at least 30% by weight of the functional fluid composition.

Suitable Fischer-Tropsch derived base oils that can conveniently be used as a base oil in the functional fluid composition of the present invention are those described, for example, in EP 0776959, EP 0668342, WO 97/21788, WO 00 / 15736, WO 00/14188, WO 00/14187, WO 00/14183, WO 00/14179, WO 00/08115, WO 99/41332, EP 1029029, WO 01/18156, WO 01/57166 and WO 04/07647 .

In one preferred embodiment of the present invention, the Fischer-Tropsch derived base oil has a kinematic viscosity at 100 ° C. in the range of 0.5 to 2 mm ² / s, preferably 1 to 1.5 mm ² / s (according to the invention is referred to as GTL gas oil or “GTL GO”).

In another preferred embodiment of the present invention, the Fischer-Tropsch derived base oil has a kinematic viscosity at 100 ° C. in the range of 2 to 4 mm ² / s, preferably in the range of 2 to 3 mm ² / s.

A particularly preferred Fischer-Tropsch base oil for use in the invention is GTL 3.

Preferably, the kinematic viscosity at 40 ° C. of the base oil composition is in the range of 1 to 30 mm ² / s, more preferably in the range of 1 to 15 mm ² / s, even more preferably between 2 and 10 mm ² / s, much more preferably from 3 to 4 mm ² / s.

It is advisable that the composition of the base oil had a kinematic viscosity at 100 ° C below 20 mm ² / s, more preferably less than 15 mm ² / s, even more preferably in the range from 1 to 10 mm ² / s, and much more preferably in the range from 1 to 5 mm ² / s, and most preferably less than 1.5 mm ² / s. Preferably, the pour point of the base oil composition is −30 ° C. or lower.

The functional fluid composition of the present invention preferably has a kinematic viscosity at 100 ° C. of at least 3 mm ² / s, preferably at least 4 mm ² / s, even more preferably at least 4.9 mm ² / s Preferably, the functional fluid composition of the present invention has a kinematic viscosity at 100 ° C. of at least 10 mm ² / s, preferably at least 7 mm ² / s, even more preferably 6 mm ² / s.

Preferably, the functional fluid of the present invention has a pour point of −30 ° C. or lower, preferably −50 ° C. or lower.

Preferably, the functional fluid composition according to the invention has a viscosity index in the range of 100 to 600. More preferably, the functional fluid composition according to the invention has a kinematic viscosity at 40 ° C. of at least 7 mm ² / s.

The flash point of the base oil composition, which is determined according to ASTM D92, can be even more than 120 ° C or even more than 140 ° C. The flash point of the base oil composition may depend on the application of the oil. Preferably, the composition of the functional fluid has a flash point of 80 ° C or higher.

The composition of the functional fluid according to the invention contains one or more additional base oils, in addition to naphthenic base oils of mineral origin and Fischer-Tropsch derived base oils. Conveniently, the additional base oil contains less than 20% by weight, more preferably less than 10% by weight, even more preferably less than 5% of the total weight of the functional fluid formulation. Examples of such base oils are paraffin-based mineral base oils and synthetic base oils, for example poly-alpha olefins, poly-alkylene glycols and the like.

Preferably, the functional fluid composition further comprises at least one other additional lubricating component in an effective amount, such as, for example, polar and / or non-polar lubricating base oils, and operating additives, such as, for example, but not limited to, metal-containing and ash-free oxidation inhibitors, metal-containing and ash-free dispersants, metal-containing and ash-free detergents, corrosion and rust inhibitors, metal deactivators, metal-containing metal-free, low-ash, phosphorus-containing and not containing phosphorus, sulfur-containing and not containing sulfur anti-wear additives, metal-containing and not containing metal, phosphorus-containing and not containing phosphorus, sulfur-containing and not containing sulfur extreme pressure additives, anti-seize additives, depressants, lowering temperature paraffin modifiers, viscosity modifiers, seal compatibility agents, friction modifiers, lubricity improvers, anti-corrosion agents cages chromophoric additives, antifoam additives, demulsifiers, and other usually employed additive packages. An overview of the most commonly used additives is given by D. Klamann, Lubricants and Related Products, Verlag Chemie, Deerfield Beach, FL; ISBN 0-89573-177-0, and in the material “Lubricating additives” M.W. Ranney, published by Noyes Data Corporation of Parkridge, N.J. (1973).

Preferably, the composition of the functional fluid according to the invention contains additives (b) that improve the viscosity in an amount of from 0.01 to 30% by weight.

Additives that improve the viscosity index (additives that improve the VI, viscosity modifiers, or additives that improve the viscosity), ensure the performance of lubricating oils at high and low temperatures. These additives give shear resistance at elevated temperatures and acceptable viscosity at lower temperatures. Suitable viscosity index improvers include both low molecular weight and high molecular weight hydrocarbons, polyesters and additives that improve the viscosity index and dispersant properties, which play the role of additives that improve both the viscosity index and dispersion. Typically, the molecular weight of such polymers is between about 10,000 and 1,000,000, more preferably from 20,000 to 500,000, and even more preferably between about 50,000 and 200,000. Examples of suitable viscosity index improvers are polymers and copolymers of methacrylate, butadiene, olefins or alkyl styrenes. Viscosity index improvers can be used in an amount of 0.01 to 30% by weight, preferably 0.01 to 25% by weight, even more preferably 0.01 to 20% by weight, much more preferably 0 , 1 to 18% by weight and most preferably from 5 to 15% by weight, based on the entire composition of the functional fluid.

A commonly used viscosity index improver is polyisobutylene. Other suitable viscosity index improvers include ethylene and propylene copolymers, hydrogenated block copolymers of styrene and isoprene, and polyacrylates such as styrene-isoprene or styrene-butadiene based polymers with a molecular weight of from 50,000 to 200,000. Preferred index improvers viscosity, contain polymethyl methacrylate (hereinafter referred to as PMMA), that is, a copolymer of methyl and alkyl methacrylates with different chain lengths. Therefore, the composition of the functional fluid according to the invention contains viscosity improvers that include a methyl methacrylate polymer. Particularly preferred PMMA viscosity index improvers are those commercially available viscosity improvers, such as Viscoplex (Viscoplex is a trademark of Rohm GmbH & CO. KG, Darmstadt, Germany), and in particular Viscoplex 7-310, Viscoplex 7- 300 and Viscoplex 7-305.

Preferably, additional antiwear additives which include metal alkyl thiophosphates, more particularly zinc dialkyldithiophosphates, typically used in an amount of about 0.4% by weight to 1.4% of the total weight of the functional fluid composition, can be used with the composition of the invention.

Other preferred antiwear additives include triaryl phosphates, such as those available from Chemtura under the trademarks Reolube OMTI, Durad 310M, Durad 110, Durad 150B, Reolube TXP, Durad 220B, Durad 620B, Durad 110B, Fryquel 150 and Fryquel 220, additives, available from Rhein Chemie under the trademarks Additin RC 3661, Additin RC 3760 and Additin RC 3680 and commercially available from Supresta under the trademarks SynOAd 8475, SynOAd 8484, SynOAd 8485, SynOAd 8478, SynOAd 8477, SynOAd 8499 and SynOAd 9578. triarylphosphates includes tricresylphosphates, such as those that meet the standard specification TT-t-656.

Other preferred antiwear additives include phosphorus free antiwear additives such as sulfur containing aliphatic, arylaliphatic or alicyclic olefinic hydrocarbons containing from about 3 to 30 carbon atoms, more preferably from 3 to 20 carbon atoms. Even more preferred hydrocarbon radicals are alkyl or alkenyl radicals, for example as described in US Pat. No. 4,941,984.

Other preferred antiwear additives include polysulfides of thiophosphoric acids and esters of thiophosphoric acids, and phosphorothionyl disulfides described in US patent No. A-2443264; A-2471115; A-2526497; 2591577 and A-3770854. The use of alkylthiocarbamoyl compounds, such as bis (dibutyl) thiocarbamoyl, in combination with molybdenum compounds, such as oxymolybdenum diisopropylphosphorodithioate sulfide and phosphoric esters, such as dibutylhydrophosphite, as an anti-wear additive, are disclosed in U.S. Pat. US Pat. No. 4,758,362 describes the use of carbamate additives to provide improved antiwear and extreme pressure properties. The use of thiocarbamate as antiwear additives is described in US patent No. A-5693598. Glycerol esters can be used as antiwear additives. For example, mono-, di- and tri-oleates, mono-palmitates and mono-myristates can preferably be used. US Pat. No. 5,034,141 describes a combination of zinc dialkyldithiophosphate, a thiodixanthogen compound and a metal thiophosphate, which leads to an improvement in antiwear characteristics. US Pat. No. 5,034,142 teaches that the use of a metal alkoxyalkyl xanthate and dixanthogen in combination with zinc dialkyldithiophosphate can improve antiwear properties. Typically, antiwear additives can be used in an amount of about 0.01 to 6% by weight, preferably about 0.01 to 4% by weight, based on the total weight of the liquid composition.

Suitable oxidation inhibitors inhibit the oxidative degradation of the functional fluid composition during use. Said failure can lead to the deposition of metal on the surface, to the appearance of sludge or to an increase in the viscosity of the liquid. Many suitable oxidation inhibitors are known, for example those described by Klamann in the book Lubricants, and for example, in US Pat. Nos. A-4,798,684 and 5,084,197. Effective oxidation inhibitors include spatially hindered phenols. These phenolic oxidation inhibitors can be ashless (metal-free) phenolic compounds or neutral or basic salts of metals and certain phenolic compounds. Typical compounds - phenolic oxidation inhibitors are spatially hindered phenols that contain a spatially hindered hydroxyl group, and these compounds include derivatives of dihydroxyaryl compounds in which the hydroxyl groups are in ortho or para position to each other. Examples of phenolic materials of this type include 2-tert-butyl-4-heptylphenol; 2-tert-butyl-4-octylphenol; 2-tert-butyl-4-dodecylphenol; 2,6-di-tert-butyl-4-heptylphenol; 2,6-di-tert-butyl-4-dodecylphenol; 2-methyl-6-tert-butyl-4-heptylphenol; and 2-methyl-6-tert-butyl-4-dodecylphenol. Other spatially hindered mono-phenolic oxidation inhibitors may contain, for example, spatially hindered ester derivatives of 2,6-dialkylphenolpropionate.

Bis-phenolic oxidation inhibitors can also be advantageously used in the composition of a functional fluid. Non-phenolic oxidation inhibitors that may be used include oxidation inhibitors such as aromatic amines, which may be used either alone or in combination with phenols. Typical examples of non-phenolic oxidation inhibitors include alkylated and non-alkylated aromatic amines, such as aromatic monoamines with aliphatic, aromatic or substituted aromatic groups with nitrogen substituents. Typical oxidation inhibitors, aromatic amines, have groups of alkyl substituents of at least about 6 carbon atoms. Examples of aliphatic groups include hexyl, heptyl, octyl, nonyl and decyl. Typically, aliphatic groups cannot contain more than about 14 carbon atoms. Amine oxidation inhibitors of the general type effective in the compositions of the present invention include diphenylamines, phenylnaphthylamines, phenothiazines, imidodibenzyls and diphenylphenylenediamines. In addition, mixtures of two or more aromatic amines are effective. Polymer amine oxidation inhibitors can also be used. Specific examples of oxidation inhibitors, aromatic amines, that are effective in the present invention include: p, p'-dioctyldiphenylamine; tert-octylphenyl-alpha-naphthylamine; phenyl-alpha-naphthylamine and p-octylphenyl-alpha-naphthylamine. Sulfonated alkyl phenols and their salts with alkali or alkaline earth metals are also effective oxidation inhibitors. Low-sulfur peroxide destructors are effective oxidation inhibitors. Another class of suitable oxidation inhibitors are oil soluble copper compounds. Examples of suitable copper oxidation inhibitors include dihydrocarbylthionates or copper dithiophosphates and copper salts of carboxylic acids. Other suitable copper salts include dithiacarbamates, sulfonates, phenates, and copper acetylacetonates. It is known that basic, neutral or acidic Cu (I) and or Cu (II) copper salts derived from alkenyl succinic acids or anhydrides are particularly effective. Preferred oxidation inhibitors include spatially hindered phenols, arylamines, low sulfur peroxide destructors, and other related components. These oxidation inhibitors can be used individually by type or in combination with other inhibitors. These additives can be used in an amount of from about 0.01 to 5% by weight, preferably from about 0.01 to 2% by weight.

Detergents used as additives can be simple detergents, or hybrid, or complex detergents. The latter additives can provide the characteristics of two detergent additives, without the need for mixing separate materials, for example, as described in US patent A-6034039. Suitable detergent additives include anionic compounds that contain a long chain of the oleophilic part of the molecule and a smaller anionic or oleophobic part of the molecule. Typically, the anionic portion of the detergent is a derivative of an organic acid such as sulfuric acid, carboxylic acid, phosphoric acid, phenol, or mixtures thereof. The counterion is usually an alkaline earth or alkali metal. Salts that contain an almost stoichiometric amount of metal are called neutral salts and have a total alkaline number (TSP, measured according to ASTM D2896) of 0 to 80. Preferred detergents include alkaline earth or alkali metal salts — sulfates, sulfonates, phenates, caroboxylates, phosphates and salicylates. Suitable alkarylsulfonates typically contain from about 9 to 80 or more carbon atoms, more typically from about 16 to 60 carbon atoms. Sulfonates described in Klamann's books “Lubricants and Related Products”, and “Lubricating Additives”, cited earlier, and C.V. are preferred. Smallheer and R.K. Smith published by Lezius-Hiles Co. of Cleveland, Ohio (1967). Alkaline earth metal phenolates are another useful class of detergent additives. These detergents are the products of the interaction of alkaline earth metal hydroxides or oxides with alkyl phenol or sulfonated alkyl phenol. Useful alkyl groups include C ₁ -C ₃₀ straight or branched chain alkyl groups, preferably C ₄ -C ₂₀ alkyl groups. Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol, nonylphenol, 1-ethyldecylphenol and the like. Metal salts of carboxylic acids can also be used as detergents. Another preferred class of detergent additives are alkaline earth metal salicylates, including monoalkyl - tetraalkyl salicylates, in which the alkyl groups contain from 1 to 30 carbon atoms. A preferred alkaline earth metal is calcium, magnesium or barium; with calcium being most preferred. Another useful class of detergent additives includes alkaline earth metal phosphates. Typically, the total concentration of detergent additives is from about 0.01 to 6% by weight, preferably from about 0.1 to 4% by weight, based on the entire composition of the functional fluid. In addition, non-ionic detergents can preferably be used in lubricating compositions. Such nonionic detergents may be ashless or low ash compounds and may include individual molecular compounds as well as oligomeric and / or polymeric compounds.

In addition, the additives may contain dispersing agents. Usually suitable dispersing agents contain polar groups associated with a hydrocarbon chain having a relatively large molecular weight. Typically, polar groups contain at least one element of nitrogen, oxygen or phosphorus. Typical hydrocarbon chains contain from about 50 to about 400 carbon atoms. Suitable dispersing agents include phenolates, sulfonates, sulfonated phenolates, salicylates, naphthenates, stearates, carbamates and thiocarbamates. Particularly effective class of dispersing agents are derivatives of alkenyl succinic acid, in which the alkenyl chain is the oleophilic part of the molecule, which provides solubility in oil. The alkenyl chain may be a polyisobutylene group, such as the groups described in US Pat. Nos. 3,172,892; 32145707; 3,219,666; 3,316,177; 3,341,542; 3,454,607; 3,541,012; 3,630,904; 3,632,511; 3787374 and 4234435.

Other types of suitable dispersing agents are described in US patents 3036003; 3,200,107; 3254025; 3275554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,703,200; 4,100,282; 5,705,458; and in EP-A-471071.

Other suitable dispersing agents are specifically used, including hydrocarbyl-substituted succinic acid compounds, such as succinimides, succinic acid esters, or succinic acid amide esters obtained by reacting an alkyl substituted succinic acid, preferably containing at least 50 carbon atoms in a hydrocarbon substituent, with at least one equivalent of alkyleneamine.

More preferred succinic acid dispersants include borated and non-borated succinimides, including derivatives of the class of mono-succinimides, bis-succinimides, and / or mixtures of mono-and bis-succinimides, in which the hydrocarbyl succinimide contains an alkylene group such as polyisobutylene having molecular weight (Mn) of from about 500 to 5000. Other preferred dispersing agents include succinic acid esters and amides, Mannich reaction alkylphenol polyamine adducts, and terminal derivatives thereof uppami and other related components. Such additives may be used in an amount of about 0.1 to 20% by weight, preferably about 0.1 to 8% by weight.

Other dispersing agents used include oxygen-containing compounds, such as polyester compounds, polycarbonate compounds, and / or polycarbonyl compounds, in the form of oligomers or polymers, ranging from low molecular weight to high molecular weight compounds.

A friction modifier, that is, a material or compound that can change the coefficient of friction of a fluid, can be effectively used in combination with base oil components. Suitable friction modifiers may include metal salts or metal complex compounds, the metals may include alkali, alkaline earth or transition metals, such as those described in WO 2004/053030.

Other useful additives include depressant additives that lower the pour point to the minimum temperature at which the fluid may flow or may spill. Examples of suitable pour point depressant additives include polymethacrylates, polyacrylates, polyarylamides, condensation products of halides and aromatics, vinyl carboxylate polymers, and dialkyl fumarate ternary polymers, fatty acid vinyl esters and allyl vinyl ethers, such as those mentioned in W302005.

Suitable seal compatibility agents include organic phosphates, aromatic esters, aromatic hydrocarbons, esters (e.g. butylbenzyl phthalate) and polybutenyl succinic anhydride.

These additives can be used in an amount of from about 0.01 to 3% by weight.

Antifoam agents can be advantageously added to the composition of the functional fluid. Such substances slow down the formation of stable foams. Typical anti-foam substances are silicones and organic polymers, such as, for example, polysiloxanes. Antifoam agents are commercially available and can usually be used in small amounts with other additives, such as demulsifiers; usually the added amount of such additives is less than 1% by weight.

Suitable corrosion inhibitors are those indicated in the Klamann book cited above. Examples of suitable corrosion inhibitors include thiadiazoles, tolutriazoles, zinc dithiophosphates, metal phenolates, basic metal sulfonates, fatty acids and amines. These additives can be used in an amount of from about 0.01 to 5% by weight, preferably from about 0.01 to 1.5% by weight, more preferably from about 0.01 to 1% by weight. Examples of suitable corrosion inhibitors can be found, for example, in US patents A-2719125; 2,719,126; and 3087932. Examples of suitable corrosion inhibitors are commercially available inhibitors under the trade name Irgamet 39, Irgamet TTA and Irgamet 42 from Ciba, and commercially available inhibitors under the trademark Vanlube 887 from Vanderbilt.

In addition, additives of an additional type, which may include one or more additives, such as, for example, demulsifiers, solubilizers, flow improvers, coloring agents, chromophore additives, and the like, may be added to the functional fluid composition of the present invention. Each additive may contain individual additives or mixtures thereof.

In addition, the present invention relates to hydraulic shock absorbers and hydraulic systems containing a functional fluid according to the invention, as well as to a vehicle containing a hydraulic shock absorber and / or hydraulic system. It is believed that hydraulic shock absorbers will have high response values even at low temperatures, while at the same time, high biodegradability and excellent low-temperature characteristics will be demonstrated during operation.

A hydraulic shock absorber (sometimes also called a damper) is a mechanical device designed to smooth or absorb a sudden shock pulse and dissipate kinetic energy. Hydraulic shock absorbers are an important part of automobile or bicycle suspension, aircraft landing gear supports and supports for many industrial machinery. In addition, large hydraulic shock absorbers are used in architecture and civil engineering in order to reduce the susceptibility of structures to damage due to earthquakes and resonance. Shock absorbers used for a structure such as a building or bridge can be part of a seismic modification or part of a new earthquake-resistant structure. In this invention, the shock absorber also provides limitation of deformation and absorption of resonance energy, which otherwise could cause excessive movement and the final destruction of the structure.

Typically, the objective of hydraulic shock absorbers is to convert kinetic energy into thermal energy, which can then be dissipated. Typically, hydraulic shock absorbers consist of a cylinder with a sliding piston inside. The cylinder is filled with fluid. A piston / cylinder combination filled with fluid is also called a damper. In a vehicle device, such as a bicycle fork, for example, described in JP-A-2004-44643, or suspension of a rear wheel of a bicycle, passenger car or heavy cargo vehicle or landing gear of an aircraft, usually the wheel suspension contains several hydraulic shock absorbers, mainly in combination with a spring compression device such as a coil spring, a leaf spring or a torsion roller. These springs are not hydraulic shock absorbers, since the springs only conserve and do not dissipate or absorb energy. If the wheel is driven horizontally, the spring can absorb upward and downward forces and turn it into heat. The hydraulic shock absorber, along with hysteresis, for example, in the tires of the wheels, dampens the movement of the non-spring mass up and down, and thus, the bouncing of the wheels is effectively suppressed.

This is achieved by converting kinetic energy into heat under the action of fluid friction as the shock absorber flows through a narrow hole such as an internal valve. The functional fluid according to the invention is particularly effective as a shock-absorbing liquid due to the fact that the specific heat of products containing base oils produced in the Fischer-Tropsch synthesis is higher than the heat capacity of a medium containing only naphthenic base oils. When the same amount of landing energy is absorbed, a fluid with a higher specific heat is heated to a lower temperature than a fluid with a lower specific heat. This allows to reduce the degree of thermal destruction of the liquid during its operation and extends the effective life of the product.

Preferably, the functional fluid composition of the present invention has a specific heat according to ASTM E1269 (at 70 ° C.) in the range of 1.0 to 3.0, preferably in the range of 1.5 to 2.5, most preferably in the range of 1.9 to 2.2 joule / g / ° C.

In hydraulic systems, the role of fluid is reduced to the transfer of kinetic energy from one location to another inside a closed system, for example, when controlling and supporting the airplane landing gear. It was found that the functional fluid compositions according to the invention are particularly effective as aviation hydraulic fluids, due to their desirable properties at low temperatures, in conjunction with the fact that the observed swelling rate of synthetic rubber is significantly reduced for the functional fluid compositions of the present invention.

Now the present invention will be described with reference to the following examples.

Examples

Comparative Example 1

The liquid composition in comparative example 1 was prepared by mixing a naphthenic base oil, the characteristics of which are shown below in table 1, with a standard additive package. The concentration of this additive package is approximately 16.5% by weight of the liquid composition. The additive package includes a polyalkyl methacrylate additive that improves viscosity, diluted in mineral oil, triaryl phosphate, BHT oxidation inhibitor (butyloxytoluene or bulihydroxytoluene) and a corrosion inhibitor - tolutriazole.

Table 1 Characteristics of naphthenic base oil Test method Units Naphthenic base oil Characteristic Vk at 20 ° C D445 mm ² / s 4.75-5.10 Vk at 40 ° C D445 mm ² / s 2.90-3.20 Minimum flash point ASTM D92 ° C 101 Minimum pour point D5950 ° C -66 Vk - kinematic viscosity

The naphthenes content of the naphthenic base oil used in comparative example 1 is determined using a combination of liquid chromatographic separation methods by HPLC, field ionization mass spectrometry (FIMS) and proton NMR for olefins. Liquid chromatographic separation by means of HPLC is carried out according to a modified method based on document IP368 / 95. The modification is to use pentane instead of hexane as a solute. In this method, the saturated and aromatic fractions of the base oil are separated according to polarity. The relative content of saturated and aromatic compounds, as well as the total percentage of extraction are shown below in table 2.

table 2 Saturated, wt.% Aromatic, wt.% Recovery, wt.% Sample Name Naphthenic base oil from comparative example 1 91.1 9.1 100,2

The FIMS method is used for the semi-quantitative determination of the concentration of hydrocarbon types in units of the number of carbon atoms and hydrogen deficiency. Classification of the type of compounds in mass spectrometry is determined by the formed characteristic ions and is usually classified by the “number z”. Moreover, the general formula for all hydrocarbon particles is given by: C _n H _{2n + z} , where n means the number of carbon atoms and z represents the degree of hydrogen deficiency. If the values of n and z are known, then stoichiometry and the hydrocarbon itself are fully described. For components present in base oils, there is a degree of peak overlap for certain types of hydrocarbons, for example, for alkylbenzenes, as well as for tetracyclic cycloparaffins z = -6. Therefore, in order to distinguish between these types of hydrocarbons, it is necessary to first divide the sample into saturated and aromatic fractions before mass spectrometric analysis. Table 3 below shows the relative proportions (%) of the components of the naphthenic base oil used in comparative example 1 in accordance with the number z in the sequence.

Table 3 Number z: 2 0 -2 -four -6 Other Total Relative% 13.65 39.04 34.90 10.76 1,54 0.11 one hundred

From the FIMS results it follows that the naphthenic base oil used in comparative example 1 contains significant amounts of materials with values of Z = 0, -2, and -4, which are assigned to mono-, di-, and tri-naphthenes. However, the FIMS method can specify only the number z, but not the exact type of structure of the molecule. Therefore, there is a possibility that olefins are present, since they can have the same mass and formula as naphthenes. In order to confirm that the molecules present in the naphthenic base oil of Comparative Example 1 are, of course, naphthenic and not olefinic hydrocarbons, ¹ H-NMR analysis ^{of the} saturated fraction was carried out to determine the mass fraction of olefins. Found that it is less than 100 ppm Therefore, we can assume that the total content of naphthenes in the saturated fraction is about 85%. Since the saturated fraction is approximately 91% of the total mass of the base oil, it can be considered that the total content of naphthenes in the base oil is approximately 76.5%.

In addition to the naphthenes content for the naphthenic base oil from comparative example 1, a mass fraction of individual carbon atoms in a saturated cyclic hydrocarbon medium was found using the Brandes IR spectroscopy method. The method determines the mass fraction of carbon atoms in each of the following media: linear paraffins (С _P ); cycloparaffins (C _N ) and olefins (C _A ). The results are shown below in table 4.

Table 4 Carbon atom distribution % C _P % C _N % C _A Naphthenic base oil from comparative example 1 42.6 51.8 5,6

Examples 1-3

The samples in Examples 1-3 were prepared by mixing the naphthenic base oil with a Fischer-Tropsch base oil in the amounts indicated in Table 6 below. The naphthenic base oil used in Examples 1-3 was the same as in the comparative example 1.

The base oil used in the Fischer-Tropsch synthesis used in Examples 1 and 2 is “GTL 3” and has a viscosity at 100 ° C. of 2.68 mm ² / s. The base oil used in the Fischer-Tropsch synthesis used in Example 3 is “GTL-GO”, that is, the gas oil produced in the Fischer-Tropsch synthesis having a viscosity of 1.255 mm ² / s at 100 ° C. GTL 3 and GTL-GO oils can be prepared by the method described in WO 2004/07647. The properties of GTL 3 and GTL GO are listed below in table 5.

Table 5 Property Test method Units GTL 3 GTL GO Vk at 100 ° C D445 mm ² / s 2.68 1,255 Vk at 40 ° C D445 mm ² / s 9,581 3,128 Density at -40 ° C D2983 SR - 50/40 Viscosity index D2270 119 - Pour point D5950 ° C -42 -51 Vk - kinematic viscosity

Used in comparative example 1, the additive package is mixed with each oil from examples 1-3 in the same quantities as used in comparative example 1.

Table 6 Example Naphthenic base oil,% GTL 3% Gas oil GTL,% Comparative Example 1 one hundred 0 0 Example 1 80 twenty 0 Example 2 90 10 0 Example 3 80 0 twenty

Tables 7 and 8 below show various physical characteristics defined for the fluids of Examples 1-3 and Comparative Example 1.

Table 7 Yield temperature (test method D5950) Viscosity (40 ° C) (test method D445) Viscosity (100 ° C) (test method D445) Example Comparative Example 1 -69 ° C 14.7 5.5 Example 1 -66 ° C 14.8 5,4 Example 2 -69 ° C 13.7 5.1 Example 3 -66 ° C 13.5 5.1

Elastomer Volume Measurements

In order to determine the swelling properties of the fluid gaskets of comparative example 1 and examples 1-3, the fluids are subjected to a standard test according to the method of FED-STD-791-3603 (70 ° C, 168 hours using elastomers that meet the technical specifications SAE AMS 3217/2 ) In each example, tests were performed three times. The average results are shown below in table 9.

As can be seen from the above table 9, in the fluid compositions of examples 1-3 (containing, in addition to naphthenic base oil, a base oil produced in the Fischer-Tropsch synthesis), there is a significantly lower degree of swelling of the gaskets compared to the liquid composition of comparative example 1 (containing only naphthenic base oil), as indicated by a reduced degree of change in the volume of the elastomer for the liquid compositions of examples 1-3, compared with the composition of comparative example 1.

Specific Heat Measurements

The specific heat of the liquid compositions of comparative example 1 and from example 1 is measured according to the test according to ASTM E 1269 at various temperatures. In the ASTM E 1269 test, specific heat was measured using differential scanning calorimetry (DSC). The test results are shown below in table 10.

As can be seen from table 10, the liquid composition from example 1 (containing in the composition of the base oil, in addition to naphthenic base oil, oil produced in the Fischer-Tropsch synthesis) has a higher specific heat capacity than the composition of the liquid from comparative example 1 (containing only naphthenic base oil in a base oil composition).

Evaporative Loss Measurements

The evaporation loss of the composition of comparative example 1 and of example 1 was measured at 71 ° C. for 6 hours using the standard ASTM 972 test. The results are shown below in table 11.

As can be seen from table 8, for the liquid composition of example 1 (containing in the composition of the base oil, in addition to naphthenic base oil, oil produced in the Fischer-Tropsch synthesis), significantly lower volumetric losses due to evaporation are observed compared to the liquid composition of the comparative example 1 (containing only naphthenic base oil in a base oil composition).

Claims (10)

1. The composition of the functional fluid containing:
(a) from 70% to 99.99%, by weight of the composition of the functional fluid, the composition of the base oil, which contains:
(i) from 50% to 95%, by weight of the composition of the base oil, naphthenic base oil;
(ii) from 5% to 50%, by weight of the composition of the base oil, base oil produced in the Fischer-Tropsch synthesis,
wherein the composition of the functional fluid has a pour point of −30 ° C. or lower. 2. The composition of the functional fluid according to claim 1, in which the content of naphthenes in naphthenic base oil is in the range from 50% to 90% by weight of naphthenic base oil. 3. The composition of the functional fluid according to claim 1 or 2, where the composition of the functional fluid has a viscosity of at least 3 mm ² / s at 100 ° C. 4. The composition of the functional fluid according to claim 1 or 2, in which the base oil produced in the Fischer-Tropsch synthesis has a viscosity at 100 ° C in the range from 0.5 to 5 mm ² / s. 5. The composition of the functional fluid according to claim 1 or 2, in which the base oil produced in the Fischer-Tropsch synthesis has a viscosity at 100 ° C in the range from 0.5 to 2 mm ² / s. 6. The composition of the functional fluid according to claim 1 or 2, in which the base oil produced in the Fischer-Tropsch synthesis has a viscosity at 100 ° C in the range from 2 to 4 mm ² / s. 7. The composition of the functional fluid according to claim 1 or 2, which has a flash point of 80 ° C or higher. 8. The composition of the hydraulic fluid containing the composition of the functional fluid according to one of claims 1 to 7. 9. The composition of the shock absorber fluid containing the composition of the functional fluid according to one of claims 1 to 7. 10. The use of a functional fluid composition according to one of claims 1 to 7 to reduce the degree of swelling of synthetic rubber.